Greddy T620z VS SBD500X VS GT3076R
 

I currently have a Greddy Turbo Kit with the smaller T518z turbo. Built motor with 10.5 compression and 3.73 FD. At 1 bar I'm making around 320whp on 93. I swapped the diff to 3.73 because I daily my 86 and drive it on the highway every weekend for at least 4 hours at 90-100 MPH + first gear is horrible once boosted.

The T518z is an excellent turbo for anyone looking to make around 300whp instant boost in any gear even in 6th. Building my motor with 10.5 compression has slightly increased lag and installing a 3.73 rear diff didn't​ help either. Now I'm not complaining, it still spools up instantaneously but I no longer can floor it without down shifting which isn't a bad thing as it forces me to get into the powerband instead of being lazy and just floor it knowing it's gonna spool anyway.

However, I'm looking for more power now but I really don't want to create anymore lag. Target is +400whp. One member here swapped the T518z with a GT3076R (90mm trim, .86 A/R, T25 IWG). He no longer owns a twin and doesn't reply unfortunately but he claimed it spooled just as quick with much more power.

The T620z is definitely gonna spool slower as the dyno sheet provided by Greddy shows and I've read people who have the T620z asking for more power which is what I'm going through now and I don't want to upgrade turbos every year. But since I've made 320 with the T518z I don't see why the T620z can't make 400whp or even 450whp.

Finally there is the SBD500X upgrade kit which claims has the same specs as a GT"X"3076R. No idea what that means and there is no detailed info about this kit other than a 58mm inducer however the GTX series spools a tad slower than the GT series which worries me even more about this kit.

The T620z and the SBD500X upgrade kits are appealing since they're a direct bolt on. The GT3076R does bolt on but I'll need a few couplers, installation kit, oil and water lines, etc. I'll probably reuse the 1 bar actuator that came with my T518z but I'm not sure if it is going to be enough to reach 400whp on the GT3076R.

So my main question is which of these 3 would provide the best spool time to +400whp? No E85 For me as it is not available here.







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I have the T620z currently. Built motor just went in, but I still haven't been able to drive it. From what @Moto-Phil tells me, 400WHP on pump gas for the T620z might be a little stretch.


I could be wrong.

It's crazy to think a T518z can make 400whp with E85 but a bigger T620z still can't make the same amount on pump gas. Let's hope someone can confirm this otherwise it's either the SBD500X or the GT3076R for me.

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I was at 290 something with the t620z on pump gas. Granted I'm an automatic, so if I was on manual, it'd be closer to 300.

The difference between a gt3076r and a gtx3076r (what the sbd500x uses) is the gtx is a ball bearing turbo while the GT is journal bearings. The gtx will spool faster but both require oil and coolant lines.

I've heard people say the same and others say that the GTX series is less efficient below 20psi. Regardless, I think SBD doesn't actually sell a GTX3076R but a turbo with the same size or "specs". Anyone from SBD still around on the forums to chip in?


I haven't​ checked if Garrett makes a GTX with a T25 housing. Will a GTX2876R be able to make +400WHP? Might be the sweet spot since it'll definitely spool faster and at 20 psi I'm pretty sure it would be in the 400hp range. best of both worlds I guess.

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True Garrett GT series turbos are dual ball bearing, not Journal bearing.

Correct on the SBD turbo, they aren't using an actual Garrett unit. I've seen lots of guys make 400 on GTX2867Rs. There is also the GTX29 series to consider.

There are no GTX2876Rs with a T25 flange and the GTX2976Rs that come with a T25 are only made in Australia and cost about $2000. I don't want to get into the mixing and matching of housings etc.

That narrows it down for me to the GT3076R and now it's either .64 or .86 housing.

How restrictive would the .64 be at top end?

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I was looking at the dyno sheets Greddy provides and they claim 430HP to the wheels at about 20 psi. Not sure why everyone is doubting the T620z... But still you can see the T518z out spools it all the way to 3750 RPM.

Lots of misinformation here.

We take a GT3076R CHRA (Ball-Bearing) and upgrade by replacing the factory cast compressor wheel for our custom Billet Wheel.

A GTX3076R is a GT3076R with Garrett's Billet Compressor Wheel. All other components are 100% identical.

We're basically making our own, cutting some cost out of the equation and reducing pricing to the consumer.

A few months ago we began testing an aftermarket ball-bearing CHRA, which we have had very good luck with. We've had zero failures or complaints thus far.

It's not Garrett brand, but we feel it offers similar performance at 50% less money. We retail this kit for $3499. We use the same custom billet compressor wheel no matter which CHRA you buy.

If you want the Garrett CHRA, it's a $500 upcharge. I personally would choose the less expensive option, as it also includes a 1-year warranty. Same as Garrett components, and you can put that $500 towards other mods.

I should add, we have made over 500whp on our 500X Kit ;)

Hence "500" X.

I sent you guys an email a couple of weeks ago asking if you could sell me a header only for my Greddy turbo kit as mine cracked along with a pre-welded oil pan. One of your representatives, Chris Riggs, replied:

"We are unfortunately unable to supply parts to non-SBD customers, are we BARELY have enough inventory for our own customer needs"

I followed up with an email last weekend asking if I could buy your 500X upgrade kit and if that would qualify me as a customer and I haven't heard back yet so I assumed that's an automatic "no". PM me here if you can make me an offer for the upgrade kit + header + oil pan.

Edit: Just realized you might be the same Chris. Please check your email.

I'll check inventory on the manifolds and see if we have one can spare to sell.:cheers: